Growth and characterization of MMA/SiO₂ hybrid low-k thin films for interlayer dielectric applications

Abstract

The methylmethacrylate (MMA) incorporated SiO₂ thin films having low dielectric constant (k = 2.97) were deposited successfully to realize new interlayer material for the enhancement of electrical performance of on-chip wiring in very large scale integrated (VLSI) circuits. We have successfully incorporated MMA monomer and eliminated the polymerization step to lower the dielectric constant of deposited thin film. The presence of peak of C=C bond in Fourier transform infrared (FTIR) spectra and carbon peak in energy dispersive (EDAX) spectra confirms the incorporation of carbon in the film due to MMA. The concentration of MMA has great impact on the peak area and full width at half maxima (FWHM) of the Si-O-Si bond, which decreases the density by low atomic weight elements and consequently decreases the dielectric constant. The surface morphology analysed by scanning electron microscopic (SEM) image shows excellent uniformity of the film. The refractive index of 1.31 was measured by ellipsometer for 0.5 ml MMA concentration film. These deposited thin films having low refractive index and dielectric constant are widely applicable for the optical interconnects and interlayer applications in integrated optical circuits and VLSI circuits.